yes, it a cue. I just read the "Oh Crap Potty training Guide" and 18 mos is not unheard of. It can sometimes take a bit longer at that age for it to completely 'click' but totally doable. I'd say nakkie for the first couple days, watch for cues. I have two kids 22 mos apart and I'm just now pt'ing my 3 yr old. It's been too crazy. I'd suggest if you can, do it now. After baby comes, it gets crazy with an infant and a toddler and it will be a while before you can have the time to devote your attention to her to help her learn her own cues mean get to the potty.